Answer: Ambiguous statement. It is unclear who will take them to school.

2) I have bought the cookies for you to take to school.

Answer: She has bought the cookies for the son to take to school.

3) I have bought the cookies that you have to take to school.

Answer: She has bought the cookies for the son to take to school. But the wording also implies the existence of three possible scenarios connected with taking the biscuits to the school. These are that: